In recent years home heating costs have risen dramatically as have energy costs in general. Among those steps taken by the homeowner to reduce these costs have oftentimes taken the form of window coverings or so-called "thermal shades". While draperies and other loose-hanging coverings for the glassed-in areas of the home and office afford some protection from the escape of heat or, as the case may be, the influx of cold from the outside, they do not provide nearly the thermal protection of a close-fitting shade, especially those which are quilted, laminated or otherwise insulated.
The problem which arises with this kind of window coverings is that of maintaining an efficient and effective seal around the window casing, especially at its sides where a good deal of leakage occurs. It is important, of course, to maintain a dead air space if possible between the shade and the glass since air itself is a fair insulator. Such is the principle used in double-pane windows. While sealing the sides can be done and, as a matter of fact, has been done many times in the past, the mechanical system used to raise and lower the shade became somewhat of a nightmare.